Cohort I: Patients receive gp100 antigen intramuscularly (IM) into each of 2 proximal extremities once every 4 weeks for up to 4 doses. (Closed as of December, 1999) Cohort II: Patients receive gp100 antigen intradermally (ID) at 5 sites on each of 2 proximal extremities once every 4 weeks for up to 4 doses. (Closed as of December, 1999) Cohort III: Patients receive gp100 antigen IM into each of 2 proximal extremities once every 4 weeks for up to 4 doses. If patients do not exhibit immunologic response or dose-limiting toxicity, they may receive a higher dose of gp100 antigen on subsequent courses.